Liquid crystal displays (LCDs) include back light units (BLUs), the BLUs classified into direct-type BLUs and light guide plate-type BLUs.
In the case of using the light guide plate-type BLU, a surface light source may be manufactured to have an area of 1 m2 and a thickness of 10 mm or less and a brightness uniformity of 80% or greater. However, as a light guide plate increases in size, a processing yield may decrease, manufacturing costs may increase, and luminous efficiency may decrease.
The direct-type lighting installation has higher luminous efficiency than a light guide plate-type lighting installation, thus, the number of light emitting diodes (LEDs) being used may be reduced and manufacturing costs of a light guide plate are saved.